28123717 has 4 divisors (see below), whose sum is σ = 28146636. Its totient is φ = 28100800.

The previous prime is 28123703. The next prime is 28123721. The reversal of 28123717 is 71732182.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 1560001 + 26563716 = 1249^2 + 5154^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28123717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28123747) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9508 + ... + 12109.

It is an arithmetic number, because the mean of its divisors is an integer number (7036659).

Almost surely, 2^28123717 is an apocalyptic number.

It is an amenable number.

28123717 is a deficient number, since it is larger than the sum of its proper divisors (22919).

28123717 is a wasteful number, since it uses less digits than its factorization.

28123717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22918.

The product of its digits is 4704, while the sum is 31.

The square root of 28123717 is about 5303.1798951195. The cubic root of 28123717 is about 304.1054754327.

Adding to 28123717 its reverse (71732182), we get a palindrome (99855899).

The spelling of 28123717 in words is "twenty-eight million, one hundred twenty-three thousand, seven hundred seventeen".